configure --with-rsh=CMD and default blocking-IO support

[Wayne Davison]

On Thu, 7 Feb 2002, Martin Pool wrote:
> A general-purpose RSYNC_OPTS variable would be more tasteful.  I think
> popt makes supporting this fairly straightforward.

That's a nice idea.  One area we'll want to be careful of is how the two
options interact.

For instance, we want to support old scripts that might set RSYNC_RSH
and then run a bunch of rsync commands.  It would be nice to make this
work without conflicting with a user's also-existing RSYNC_OPTS var.  A
potential solution is to ignore RSYNC_OPTS if RSYNC_RSH is set (which
also serves to wean people away from RSYNC_RSH if they want to be able
to set other default options).

Another potential problem area is how to override already-set options.
If someone wants to put -a into their RSYNC_OPTS variable, how can they
then turn it off?  I suppose we could just say that the user gets what
she deserves in such a case.

So, perhaps I'm trying to solve a problem that isn't really all that
important.  Just having the ability to set the default remote shell and
its IO mode might be good enough for most people, and we let the rest
use shell scripts or aliases, like you said.

I could trim down my last patch to avoid the extra RSYNC_RSH parsing if
you'd like to just apply the other part of it.  Or, feel free to tweak
it yourself -- it should be pretty easy.

..wayne..